1. Field of the Invention
The invention relates to a digital-dimming method and module for dimming operation of a lamp, more particularly to a digital-dimming method and module that eliminates high ignition voltage and high current spikes during lamp operation.
2. Description of the Related Art
A conventional digital-dimming control module controls dimming operation of a cold cathode fluorescent lamp of a liquid crystal display by generating a driving signal that corresponds to the duty cycle of a square wave low frequency dimming gating signal. FIG. 1(A) to 1(C) illustrate a voltage (VL) across and a current (IL) through the cold cathode fluorescent lamp.
Although the conventional digital-dimming control module achieves its intended purpose, since the square wave low frequency signal (VLFD) varies abruptly between low and high voltage levels, the cold cathode fluorescent lamp is struck repeatedly with high ignition voltage (VP) and high current spikes (IP) during the dimming operation. This significantly shortens the service life of the cold cathode fluorescent lamp.